DEUTERIUM ABUNDANCE AND BACKGROUND-RADIATION TEMPERATURE IN HIGH-REDSHIFT PRIMORDIAL CLOUDS

Measurements of the deuterium abundance in the early Universe provide a sensitive test of the 'standard' Big Bang cosmology. The probable de tection of deuterium absorption by a gas cloud between us and a distan t quasar suggests an abundance much greater than estimated from observ ations in the Milky Way, and consistent with the amount of presently o bserved luminous matter comprising all the baryons in the Universe. Th e same spectra imply a cosmic background temperature for the early Uni verse which is consistent with our expectations from standard Big Bang cosmology.